[unreadable] [unreadable] The potential for the use of stem cells for regenerative medicine has produced considerable excitement. Laboratory studies have shown that it may be possible to produce functional replacements for diseased or injured tissues. However, there are still a number of scientific hurdles that must be overcome if such therapies are going to be realized. The first and most intensively studied aspect of stem cell biology are the mechanisms by which stem cells are transformed into cells with distinct physiological functions. This area of stem cell research will not be addressed in this proposal. Instead, the second area of investigation, namely how to produce enough cells from a given number of stem cells to be of practical use in creating tissues for regenerative medicine. It is assumed by many investigators, that a virtually unlimited number of stem cells can be produced in simple culture systems to meet all therapeutic requirements. This belief is based on observations of the ability of stem cells to self-renew in culture. The conventional cell culture environment does not resemble the in vivo environment in which the stem cells normally exist and therein lies the problem for large scale growth of stem cells. In vivo, stem cells are maintained in largely quiescent state. Most cell divisions lead to the production of a stem cell and a daughter cell which will continue to divide to eventually produce a tissue. The numbers of stem cells actually change very little. This situation is thought to have evolved to minimize the possibility of mutations which could lead to uncontrolled growth, ie. cancer. In this proposal, we intend to utilize the NASA-designed Rotary Cell Culture System to mimic the normal in vivo environment of stem cells so that the product of the culture is daughter cell or committed progenitor which can be harvested and stimulated to grow into a tissue which can be utilized therapeutically. The RCCS is ideally suited to reproduce the 3-dimensional microenvironment that exists in the human body. By co-culturing supporting cells with stem cells on a polymer scaffolding material, we will create a culture system which will allow the long term maintenance of stem cells while promoting the production of progenitor cells which can be continuously harvested in a controlled manner for use in tissue engineering applications. PUBLIC HEALTH RELEVANCE: This project is aimed at producing a stem cell culture system which can maintain adult stem cells in a specialized environment to maintain them for long periods of time and stimulate the production of large numbers of progenitor cells for regenerative medicine. By allowing scale-up of therapeutic cell production, this project will help enable the use of stem cells for therapeutics which heretofore has been confined to very small scale research applications. [unreadable] [unreadable] [unreadable]